The present invention relates to a heat-fused unitary ferrule and a method for producing it.
There are two kinds of parts for arraying fibers. One is a fiber array for connecting a fiber with another optical part, and the other is a MT connector for connecting a fiber with another fiber.
As a material for a fiber array, glass or silicon is generally used because most optical parts, such as a wave guide, to be connected to the fiber array have low heat expansion rate. Recently, development of a low-cost glass material having high quality has been proceeding, and glass is most popular as a material for a fiber array at present.
In a fiber array having a conventional V groove, a fiber was positioned on a V groove, the V groove and fiber were put between substrates for fixing the fiber, and the fiber was fixed using an adhesive or the like.
However, a fiber array using an adhesive sometimes had exfoliation on the joined surface because of changes in environmental conditions such as humidity and heat.
Moreover, a highly purified filler is added thereto for the purpose of lowering a hardening shrinkage rate so as to decrease deterioration by hardening shrinkage of the adhesive, and a silane coupling agent is added thereto for the purpose of improving adhesive strength. Thus, the adhesive used for fixing the fiber is so special that it is very expensive.
Furthermore, assembly of a conventional fiber array requires simultaneous performance of pressing a fiber down to a groove for fixing the fiber and pressing the second glass substrate down to the first glass substrate. The assembly was so complex that it required jigs, tools and skilled workers.
On the other hand, MT connector is low-priced and has high dimensional preciseness because it is generally made of plastic. Therefore, a large quantity of MT connectors are used as connectors for connecting a fiber to a fiber. However, it cannot be suitably used for connecting a fiber with an optical element such as a fiber array because of a high coefficient of thermal expansion.
Since a plastic connector does not transmit ultraviolet radiation, a heat-hardening type resin is used for fixing a fiber. Therefore, its productivity is poor. Particularly, there is a problem of long hardening time when connecting fibers at a work site.
The present invention solves these conventional problems and aims to provide a heat-fused unitary ferrule having high bonding strength, high water resistance high productivity, and a low price, and a method for producing it.